An internal combustion engine typically includes an engine block that at least partially defines one or more cylinders. A piston is reciprocatingly disposed within each cylinder and, together with a cylinder head, forms a combustion chamber. A mixture of fuel and air is introduced into the combustion chamber and is compressed by the piston in preparation for combustion. When combustion takes place, the expanding gases force the piston downward to rotate a connected crankshaft, thereby converting chemical energy into kinetic energy. During an ensuing exhaust stroke of the piston, byproducts of the combustion event are displaced from the combustion chamber to the atmosphere.
Although effective, many losses may be associated with the combustion process described. One such loss is due to a necessary clearance between an outer surface of the piston and an inner surface of the associated cylinder. During a compression stroke of the piston and during combustion, some of the compressed and expanding gases leak through this clearance into the space below (i.e., into the crankcase). This leakage of gases is commonly known as “blow-by”. During operation of the engine, the blow-by gases build within the crankcase, resulting in a high pressure region that acts against movement of the piston and reduces engine efficiency. To relieve this pressure and improve engine efficiency, a crankcase ventilation system is usually implemented.
One such crankcase ventilation system is disclosed in U.S. Pat. No. 5,450,835 (the '835 patent), issued to Wagner on Sep. 19, 1995. The '835 patent discloses an oil separator for reducing oil carryover from the vent port of the crankcase of a diesel engine. The separator includes a cylindrical housing filled with a filtration material, and having both an inlet and an outlet in its upper portion and a downwardly disposed frustro-conical wall that defines an annular chamber between its outer surface and the inner walls of the housing. The annular chamber defines a helical flow path through the filtration material in the housing for a stream of oil laden air admitted through the inlet of the housing. Oil droplets are removed from the stream of air as it moves through the helical path both by impingement against the filtration material, and then by centrifugal impingement against the inner walls of the housing. At the end of the helical path, the stream of air is directed along a hairpin turn through an opening in the frustro-conical wall and from thence into a double-back path before exiting the housing, thereby removing still more entrained oil droplets. The resulting filtered stream of air may be directed into the engine draft tube or the air filter by means of a pipe. The separator also includes an oil drain conduit for conducting liquid oil collected by the filtration material into the oil pan of the engine.
Although perhaps somewhat effective at venting a crankcase, the system of the '835 patent may have problems with water condensation. That is, water, which may be entrained within the air from the crankcase, may condense on the cooler walls of the separator and associated passages. And, because of the location of the oil drain conduit, the condensed water may drain back to the oil pan of the engine, where it may mix with and contaminate the oil therein.
The disclosed ventilation system is directed to overcoming one or more of the problems set forth above.